


Sleeping Arrangements

by CatKing_Catkin



Category: Undertale (Video Game)
Genre: Angst, Body Horror, Body Modification, Emotional Hurt/Comfort, Established Relationship, Gaster Blaster Papyrus, Gaster Blaster Sans, Gift Fic, Hopeful Ending, Hurt/Comfort, Literal Sleeping Together, Love, M/M, Poor Sans, Post-Pacifist Route, Protective Grillby, Sans Has Issues, Sans Needs A Hug, Sharing a Bed, Transformation, Whump
Language: English
Status: Completed
Published: 2016-04-16
Updated: 2016-04-16
Packaged: 2018-06-02 15:42:07
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,074
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/6572056
Author URL: https://archiveofourown.org/users/CatKing_Catkin/pseuds/CatKing_Catkin
Summary: <blockquote class="userstuff">
              <p>Written for the prompt "Sansby, but in the GB AU - Grillby finding out about Sans' condition."</p><p>Life on the surface is wonderfully rich and strange, but also terribly busy. Even so, despite how new their relationship is, Sans and Grillby manage to make time for it. Sans doesn't often stay over, but when he does, Grillby always has room for Sans' toothbrush on the sink and for Sans himself in the bed. </p><p>One night, this gives him an up-close view of a side of Sans that he couldn't possibly have imagined. Sans hadn't expected to still be subject to these brutal transformations even on the surface, and just wants to get through it without hurting one of his friends. For his part, Grillby just tries to keep calm, ease the pain, and think about where to go from here.</p>
            </blockquote>





	Sleeping Arrangements

**Author's Note:**

  * For [1nky](https://archiveofourown.org/users/1nky/gifts).



Sans didn’t often stay over. Ordinarily, that was fine with Grillby. They both had things they worried about that weren’t easy to carry with them. For Grillby it was the restaurant; for Sans it was Papyrus. They were both happier when they were able to return to those things at the end of each day. They were both happier with routine. Maybe one day that would change. It suited them fine for now.

Still, it happened every so often. Maybe the weather would be too bad for Papyrus to come and pick Sans up, or maybe Papyrus would be staying over with Undyne instead. Sans had a toothbrush that he left at Grillby’s apartment over the restaurant, and he otherwise didn’t take up much space. On nights when Sans stayed over, it would simply be a matter of walking up the stairs together, rather than alone.

Their relationship, for lack of a better word, was still a comparatively new one. The rich strangeness of life on the surface often meant that it was put on the backburner, set to the side. And Sans was still, in his own way, incredibly nervous and shy about certain things. So Grillby would never admit how happy it had made him when things progressed from Sans sleeping on the couch to Sans sharing his bed. He didn’t need to admit it, either. A slow burn was best for the skeleton, and that was how Grillby went through most of life anyway.

The two of them really did share a bed quite nicely. Sans always curled against Grillby, soaking in the elemental’s ambient warmth, and Grillby was happy to hold him. In turn, Grillby could be a somewhat restless sleeper, but Sans slept deep and still enough that it never woke him. So on those rare nights when Sans stayed over, the two of them usually passed the night together restfully, peacefully. Rest and peace were otherwise still rare enough for the two of them, even on the surface.

Such was how it usually went.

Tonight, something was different. Something was wrong. Sans had been hesitant and on edge all night, distracted from any pretense at conversation. Grillby never eavesdropped, but Sans had definitely _sounded_ tense in what snatches he’d inadvertantly overheard of his talk with Papyrus, as he stood outside the restaurant waiting in vain. It got to the point where Grillby got so worried that he offered to drive Sans home himself, despite the fact that his truck wasn’t in terribly good shape. It was a minor miracle if he could get his own shopping done without his niece's help on a weekly basis.

They both knew it, and Grillby suspected that this was why Sans shook his head at the offer and tried valiantly but vainly to smile. “nah, it’s cool. we’ll make it work. thanks anyway, grillby.”  

So they climbed the stairs up to Grillby’s little apartment together. Sans was dragging his feet a little bit, and Grillby pretended not to notice. They each got ready for bed in their own ways. The shower only ever got used when Sans was over. It had come with the unit.  

One thing Grillby absolutely couldn’t ignore, however, was when Sans made to settle himself down on the couch for the night instead. _“Sans…?”_ he asked, and some of the hurt must have shown on his face. Sans looked immediately apologetic, but neither did he make any move to rise.  

“sorry,” his friend said, scratching at his skull and looking away. “sorry. just, ah, got kind of a headache tonight. and you know you’re, uh…kinda bright.”

_“Oh.”_

Grillby had never thought of himself as one who burned all that bright. He certainly never thought it could cause anyone discomfort. So he frowned, staring down at the floor and feeling a sudden, sharp _shame_. It pierced all the way down to his soul, as bad as a sudden dousing of water. The way Sans looked immediately apologetic only made it worse. “i’m sorry, pal,” he said, starting to rise. “i didn’t mean…it’s fine, y’know, it’s…”

 _“No.”_ Grillby quickly waved a hand, motioning for Sans to stay down. _“There’s no need to apologize. I understand.”_  Though it didn’t make this any less awkward, he did. It was a relief to have an excuse to turn away, even if only to head towards the closet. _“Let me get you a clean blanket.”_

Even the act of doing _something_ let him feel a little steadier, and Grillby felt a little less uncomfortable and strained as he returned to Sans’ side to tuck the blanket around his shoulders. When Sans still looked apologetic and uncertain, Grillby didn’t hesitate before leaning forward to softly kiss his forehead. _“It’s all right,_ ” he said, and knew he meant it this time. _“Sleep well. I’ll see you in the morning.”_

Sans tilted his skull against the kiss, as he always did. While he didn’t look entirely reassured, he still looked grateful for the attempt. “yeah,” he said. “you, too.”  

Grillby turned out the lights in the living room, lingered for a moment until he saw the dim glow of Sans’ eyelights go entirely dark, and then retired to his own room.  

Sleep didn’t come easily, though. Judging from the faint rustling and other sounds of movement he could hear from the living room, it wasn’t any easier for Sans. Not for the first time, he wished there was something more he could do. Healing magic could recover HP. Unfortunately, if his food wasn’t enough to heal the ordinary aches and pains of life, there wasn’t much more Grillby was capable of doing. So much of his energy went into keeping the restaurant going. It didn’t leave much else for other things, no matter how important.

It was half past midnight before his view of his bedside clock was obscured by a shadow. Grillby heard the faint, soft rustling sounds of a body moving carefully. The silhouette dimly outlined in his own ambient light, however, was unmistakable.

The bed dipped and creaked a little beneath Sans’ weight, as the skeleton moved over to lay himself down beside the elemental. He pressed close, near enough that Grillby could feel him shaking a little. So he didn’t hesitate before wrapping his arms around Sans and drawing him against his chest. Sans clung tightly to him with something like fierceness, pressing his head against Grillby’s chest. Yet even as he did so, he whimpered faintly in pain, and it was only then that Grillby remembered his friend’s earlier words.

 _“What about your head?”_ he asked, running a hand carefully along the back of Sans’ skull.

“s’fine,” Sans murmured. “it’s better like this.” He didn’t sound it. His voice sounded tight and strained. Grillby sat up slightly, and wasn’t remotely reassured when Sans tried to hold tighter to him.

_“Sans, I think I should call the hospital. You don’t look well…”_

_“No!”_

Grillby flinched, his grip tightening and his eyes widening in alarm. He’d never heard Sans’ voice sound like that before. He’d never heard him sound this _scared_ before. He barely heard him as Sans stumbled on, panicking, _pleading_. “grillby, c’mon, just…just _don’t_ , it’ll be fine, papyrus s-said it’d be fine, don’t _leave_ …”

His words were cut off by an echoing, splintering _crack_. Grillby and Sans pulled sharply away from each other, and in the light of Grillby’s own flames, he saw that Sans’ silhouette suddenly wasn’t so familiar anymore. His skull was wrong and strange and sharp and seemed to be _shifting_ …

Sans looked up at Grillby, and the familiar pale white lights in his eyesockets had been consumed by twin blazes of smoky blue fire. That was all Grillby had time to register before Sans flung himself off the bed and made a mad scramble towards the door. Grillby heard him gasping and whimpering in pain and panic, and that was all the motivation he needed to be jolted from his stupor to chase after his friend. _“Sans!”_

_“S-Stay back!”_

Again, that voice that wasn’t Sans’ voice. This time Grillby didn’t let himself be deterred. He kept his distance in a possibly-vain effort to keep Sans from panicking further, but he didn’t back off or retreat. Whatever was happening, he couldn’t leave Sans. He _wouldn’t_.

Fortunately, or perhaps quite the opposite, whatever was happening was finally leaving Sans in too much pain to go anywhere. A second, resounding crack maybe Grillby gasp in alarm, and then Sans collapsed to the floor in an ungainly heap with a yowl. He was within a couple of feet of the front hallway, but judging by the way his leg was suddenly bent so wrongly it might as well have been miles. It was only then that Grillby noticed that already, he was noticeably larger than he had been.  

Sans was changing, morphing, and Grillby didn’t know why or how to stop it. So perhaps he could be forgiven for doing the only thing that made sense, which was moving towards the phone. Perhaps he could be forgiven for saying the first thought that came to him, which was: _“I’m calling the hospital!”_

 _“No!”_ Sans cried, and only the fact that there was no one else in the apartment with them left Grillby certain that it _was_ Sans who’d spoken. His voice echoed strangely and was edged with a growl. But when the monster collapsed at the other end of the living room lifted his head, there were tears of bright blue magic falling from its eyesockets, and its gaze was still an unmistakably pleading one. _“Don’t, please! They can’t know, they can’t, don’t_ leave _, Grillby…”_

Sans had been trying to support himself on one arm while he’d spoken, the better to look up at his friend. That arm suddenly gave out with a nauseating crunch, and Sans collapsed back to the floor with a cry. The words had left Grillby feeling as though he were drowning. That howl of agony, however, was fuel. He crossed the floor in a few long, sure strides, before kneeling down next to Sans and reaching out to rest a hand on his mutated skull.  

 _“I won’t,”_ he said. _“I’m here.”_

Sans closed his eyesockets. He let out a long, shuddering sigh, and then nodded his apparent acceptance.  

_“Is there anything else that I can do?”_

_“Hah…h-hate to ask this…but water. P-Please.”_

Sans might have been the only one to ever use the shower in the apartment, but Grillby’s sink did get some use. He could still produce dirty dishes when on his own, after all, even if he never let them linger. So he nodded, said _“Be right back”_ when he wasn’t sure if Sans saw him do so, then got to his feet and hastened into the kitchen. Grillby remembered to pull his dishwashing gloves on just in time before he turned on the sink, and this was for the best. In his panic, especially with those _sounds_ still coming from the living room, he turned the faucet on much too high at first and would have badly burned his hands if not for the gloves.  

He got a glass filled and brought it back out to the living room. Sans stared up at him, his gaze feverish and unfocused. Fortunately, he remembered enough to reach out for the cup. Unfortunately, Grillby could see immediately that his hands were no longer fit to hold much of anything. They were barely hands at all, they looked more like _paws,_ and they were tipped with claws that gleamed faintly in the dim light of the living room.  

 _“Let me,”_ Grillby said, kneeling down beside Sans again and carefully tipping the glass towards his open, panting jaws. Some of it splashed on the floor - cleaning that up later would take care. Most of it made it in, and Sans shuddered bodily in apparent relief.  

He was noticeably, undeniably bigger. Sprawled out on the floor as he was, Grillby could still tell that Sans was possibly as tall as he himself was, now. His limbs were longer, too, unnaturally so and bent in all the wrong ways. The elemental knew from a lifetime of serving dogs that when Sans finally did find the strength to rise, it would be on all fours.

None of this was okay. However, so many surprising facts were piling one on top of the other that Grillby was finding it perversely easier to manage. Individually, there were too many impossible details to take in. So he just tried to absorb their impossibility in one wave, like keeping your balance on a raft, and kept all of those thoughts to himself since Sans obviously had other things to worry about.

 _“Better?”_ he asked when the glass was empty.  

 _“Y-Yeah…”_ Sans croaked, slumping back again.  

 _“What about Papyrus? Surely you agree that he should know what’s happening to you.”_ Whatever was happening to him, of course.

Sans bared his fangs. It took Grillby a second to recognize the attempt at a smile. _“He’s…hah. He’s probably changed by now, too. Undyne’s in for…hah…for a rough night. He didn’t think it c-could happen up here. Wanted to…”_ Whatever Sans or Papyrus had wanted to do, Grillby didn’t get the change to hear it. Sans’ voice trailed away to a shuddering growl, and for a wild moment of panic, Grillby was afraid that these would be the last words Sans would ever say to him.  

He did the only thing he could think to do, he did what so often seemed to be the only thing he could do for Sans. Grillby pulled him closer, mutated and increasingly bestial as Sans was, and let his soul burn brighter for his friend. Thankfully, Sans’ eyelights slowly grew less indistinct in reply. It was only for a moment, though, before they became blurred by fresh tears.  

 _“I only w-wanted to believe him…it_ hurts _, Grillby…”_

 _“I know,”_ Grillby murmured fretfully, because that much was plain to see. _“I’m here,”_ he added, because that really was the only thing he knew of that seemed to help.

 _“C-Can’t stop it…”_ Sans arched off the floor as his spine cracked loudly enough to make Grillby flinch. The noise the skeleton made was the noise of a monster in too much pain to scream. He sprawled back on the floor, panting, shuddering, and words seemed lost to him until Grillby leaned forward to press a kiss between his eyesockets. _“But it hurts less…when you’re here…just didn’t want…I d-didn’t…”_

 _“You wouldn’t have hurt me,”_ Grillby said firmly, showing mercy and taking a guess. _“I wouldn’t have allowed it.”_

Again, Sans looked up at him to offer that gruesome smile. Now Grillby could see the signs of his friend that remained in that changed face, and knew how heartfelt the emotions behind that smile still were.  

So Grillby, in turn, felt safe enough to ask the question that felt as though it had been weighing on him for a lifetime. _“Is this permanent?”_ Sans sounded much too familiar with this entire brutal process for it to be anything like that. Grillby still needed to hear the words out loud. He needed one modicum of certainty in this nightmare, for both their sakes.

_“Never has been yet…”_

Grillby cut him off, gently but insistently as he stroked a hand along Sans’ spine, through the tatters of his increasingly ruined shirt. _“Then there’s no reason that it would be now. And until this passes, Sans, I will take care of you. You can trust me.”_

_“Always have…always…”_

Sans made one last, valiant effort to speak, before his own willpower was no longer enough to force that skull to be capable of even producing speech. Grillby let himself believe that the words sounded like _I love you_. He murmured the same in reply, over and over again like a prayer, as he settled down to keep watch over the monster he loved.  

It felt as though it took an eternity for the transformation to end, yet a deliberate glance at the clock told Grillby that it had only been a couple of hours. The end result was Sans, slumped on the floor in a mess of torn and shredded clothes, gouges dug into the floor from his claws. The end result was Grillby, sitting slumped against the wall beside his friend, gently stroking Sans’ snout in an attempt to ease the passage from unconsciousness to sleep.

Sans’ “new” body, for lack of a better word, was something like a bear’s and something like a wolf’s, and just a shade larger than Greater Dog in full armor. Even getting him out the front door like this would be a trial, if it was even possible without causing a panic or serious property damage. Grillby really would need to take care of him here until this passed. At least if anyone could be trusted to do the same for Papyrus, it was Undyne.

Thoughts came easier from there. The mountain of impossible things had stopped growing, so now he could address them as one impossible thing at a time. Any problem could be managed when broken down to one point at a time. That was how he’d so often lived his life. Consuming one twig at a time wouldn’t get you a large blaze, but it would get you a steady one. Underground, that was often what was best. Above ground, it was still often what was best as well.

Somehow, the point he found himself addressing first was setting up a new sleeping arrangement. This he accomplished by gathering up the blankets from the couch and from his bedroom. All together, they were enough to more-or-less cover Sans. Sans’ skull was much heavier now, but Grillby didn’t need to lift it too far before he was able to settle it back in his lap. The pillows he had managed to retrieve, he piled around himself instead, to try and wait out the night as comfortably as possible from a spot sitting against the wall.

He’d had worse nights. And when Sans let out a noise that Grillby recognized as a contented whuff from years of serving the Dogs, it already seemed a little bit better.

 _“I love you, too,”_ he whispered sleepily, kissing Sans gently just over one eyesocket. _“Sleep well.”_

They would figure this out in the morning.  


End file.
